Some suggested the president did not want to alienate whites who voted for him out of a sense of racial grievance. Others said he was offering his white nationalist supporters a wink and a nod. Yet another concluded advisers like Stephen K. Bannon must be influencing the president in dark ways.

But there is an alternate explanation, one that is espoused by many on the right and repeated on an almost daily basis in the conservative news media that consumes so much of the president’s attention and energy.

In this version of events, a violent and dangerous left fringe is ignored by news media that would rather elevate far-right extremism as the nation’s more urgent threat. This view of the left as unhinged and anarchistic has become popular with some Republicans who insist that Democrats still refuse to accept Mr. Trump. They seek to stoke powerful emotions behind perceptions of excessive political correctness and media bias.